All music is based to a large extent on harmonic progressions, namely sequences of combinations of notes or chords which define underlying harmonic changes. However, conventional Western musical notation is based on a stave, known in the USA as a staff. An example of such notation is illustrated in FIG. 1, which represents in conventional musical notation the first sixteen bars of Bach's First Prelude from the Well Tempered Clavier Book I. The chord described by each section of music is shown above the stave.
Musicians and composers have long known about the inadequacies of stave notation with respect to chords and harmonies. For example, the harmonic relationship between sequential chords cannot be indicated on a stave, and it is therefore difficult to appreciate any patterns that may be present within a chord sequence.
Newcomers to music often find it difficult to understand and recall the appropriate patterns in chord sequences. For example, several notes may be played simultaneously to produce a chord, but if one of those notes is omitted or replaced by another note, the chord may change significantly. Such subtle differences are difficult for beginners to observe in standard musical notation.